This invention relates to an electrically power assisted bicycle and more particularly to an improved bicycle of this type, the positioning of the driving components therefore, and an improved arrangement for facilitating battery servicing.
Electrically power assisted bicycles of the type shown in U.S. Pat. No. 5,266,501, issued Jul. 13, 1993 and copending applications, Ser. Nos. 08/026,868 filed Mar. 5, 1993, now issued as U.S. Pat. No. 5,375,676 on Dec. 27, 1994; 08/059,540 filed Mar. 10, 1993, now issued as U.S. Pat. No. 5,370,200 on Dec. 6, 1994 and 08/128,799 filed Sep. 29, 1993, now issued as U.S. Pat. No. 5,474,148 on Dec. 12, 1995 all of which are assigned to the assignee hereof, have a number of advantages. In the construction shown in each of those applications and the aforenoted patent, the bicycle is provided with a conventional pedal mechanism operated by the rider.
In addition, there is provided an electric motor powered by a battery and controller arrangement for assisting the operator effort in response to the pedal input force so as to make the riding of the bicycle easier while at the same time maintaining its ability to provide exercise for the rider. In the arrangements shown in those applications, the motor and its driving transmission are disposed in a generally vertically orientation either aligned with or beneath the seat pillar. The battery and controller are disposed in a somewhat horizontally extending position along the main frame member that extends from the head pipe downwardly toward the pedal mechanism. Although this arrangement has a number of advantages, it tends to move the center of gravity of the bicycle generally forwardly of the crank mechanism and also somewhat elevates the center of gravity. Of course, by positioning these mechanisms below the crank axis, the aforenoted problems could be avoided but this would then substantially restrict the ground clearance for the bicycle.
It is, therefore, a principal object to this invention to provide an improved layout for the electrical power assist components of an electrically power assisted bicycle so as to improve the balance and maintain a practical but low center of gravity.
One way in which the aforenoted objects may be met is by positioning a battery case behind or adjacent the seat pillar and positioning the battery or batteries in this case. However, this type of arrangement can make it more difficult to access the batteries for service.
It is, therefore, a still further object to this invention to provide an improved battery carrying arrangement for an electrical power assisted bicycle wherein the batteries are positioned so that they can be easily serviced.
It is a further object to this invention to provide an improved movable seat arrangement for an electrically assisted bicycle so as to facilitate servicing of the components of the bicycle.